JP6420877B2 - Infrared presence detection by modeled background difference - Google Patents

Description

  The present invention relates to sensors, and more particularly to temperature sensitive devices.

  Infrared (IR) detectors, such as far-infrared detectors, can be operated with additional optical elements such as multifocal Fresnel lenses. For example, a pyroelectric detector conventionally comprises two heat sensing elements connected to each other. These two heat sensing elements cancel out commonly received radiation such as incident sunlight, so an optical system that irradiates only one of the two elements with a locally moving heat spot, for example, human radiation. is necessary.

  FIG. 1 is a schematic side cross-sectional view of an exemplary detector 100 configured to detect the position, movement, and / or orientation of a living organism (eg, a human) within a surveillance space. In general, the term “monitoring space” refers to a physical area (eg, a room, hallway, outdoor area, etc.) in which the detector 100 is located and in which the detector 100 can potentially detect organisms. Point to. The field of view (FOV) of the detector represents the range in which the detector can sense a warm object and may be part of the monitoring space or may include the entire monitoring space.

  The detector 100 includes a sensor module 102 that includes one or more temperature sensitive devices (eg, thermopile) and a lens array 104 that at least partially covers the sensor module 102. The lens array 104 includes a plurality of lenses, each of which is arranged to direct incident thermal energy from the monitoring space to at least a portion of the sensor module 102. Each individual lens directs incident thermal energy from one of a plurality of different physical zones in the monitoring space to the sensor module 102.

  The integrated circuit 106 may form a computer-based processor, computer-based memory storage device, and / or other circuitry in various implementations to perform and / or perform one or more of the functions described herein. / Or may assist. In order to connect the electrical components of the detector 100 to external components, electrical conductors (eg, traces extending along the top and / or bottom surface of the substrate 110, vias 108 extending through the substrate, solder bumps 112, etc.) are provided. Provided.

  A temperature sensitive device, such as a thermopile or photonic detector, is generally operable to produce a direct current (DC) output that is approximately proportional to the amount of thermal energy received by the temperature sensitive device. The DC output produced by such a temperature sensitive device is generally kept approximately constant as long as the amount of thermal energy delivered to the temperature sensitive device is approximately constant. An increase in the amount of thermal energy delivered to the temperature sensitive device generally results in a proportional increase in the DC output produced by the temperature sensitive device. Similarly, a decrease in the amount of thermal energy delivered to the temperature sensitive device results in a proportional decrease in the DC output produced by the temperature sensitive device. The DC output from the temperature sensitive device may be a DC voltage or a DC current.

  Current motion detectors typically employ pyroelectric materials, often with lens array 104, to detect movement of people in the room. Pyroelectric materials generate signals when incoming thermal radiation changes (from a heat source such as the human body). Mathematically, pyroelectric detectors generate an electrical signal that is derived from the time derivative of the incoming heat flux. Thus, when a person enters or leaves the detector FOV, the heat flux changes and each signal is generated. The amplitude of the signal depends on the temperature of the heat source and the so-called filling factor of the FOV. The higher the temperature of the heat source and the greater the heat source occupies the detector FOV, the higher the resulting signal.

  A warm object radiates heat that can be sensed by a thermal sensor such as a pyroelectric sensor, a thermopile, or a bolometer. When an object is moving through the field of view of such a sensor, the amount of radiation changes over time. The background can be removed from the signal in order to distinguish the aging (signal) due to the movement of the object from the aging (background) due to the local heat source where the temperature and thus the amount of radiation changes. This is called background difference.

  Conventionally, pyroelectric detectors implement a combination of scrambled optical elements and at least two spatially spaced sensing elements. The scrambled optical element divides the portion of the FOV through which the object is moving into segments so that the net radiation change in one of the elements is fast enough to be sensed by the individual elements. The net radiation visible is significantly different. This approach is illustrated by FIG. Since the at least two sensing elements 221, 222 are coupled, the commonly received radiation is canceled by the electrical outputs 231, 232 and does not fluctuate the signal 230 obtained over time 240 at all. For example, if the environment is heating or cooling, the radiation dose increases or decreases, but is not perceived because it is commonly viewed by both elements. In order to generate the signal 240 in that sensing element combination, one sensing element 221 must view a different radiation dose than the other sensing element 222.

  In order to observe the movement of an object within the sensor's field of view, the radiation received by the sensor varies both spatially and temporally. This is realized by a scrambled optical element that projects the position of an object on one of the elements 221 and 222 according to the position of the object in the FOV. Movement of the object through the FOV results in an unbalanced change of radiation at the sensing element and a non-zero signal 240 is generated. In general, an object must change position from one zone (A / B 210) to another (B / A 210) in order to be sensed. Objects that remain in one zone are not sensed.

  However, conventional single element pyroelectric detectors are unable to sense the DC component of the received radiation and thus use modulated radiation to provide output to the back-end processing electronics. The industry therefore needs to overcome one or more of these limitations.

  Embodiments of the present invention provide infrared presence sensing with modeled background differences. Briefly described, the present invention is directed to a motion sensing device comprising an infrared (IR) sensor configured to receive a signal IR from a warm object and a background IR and generate a DC output. . The first conversion filter receives a direct current output and generates a filtered background. The second conversion filter receives the direct current output and generates a filtered signal. The rating compares the filtered signal with the filtered background and generates a result signal based on the detected difference between the filtered signal and the filtered background.

  Other systems, methods, and features of the invention will be or will be apparent to those skilled in the art upon review of the following drawings and detailed description. All such additional systems, methods, and features are intended to be included herein, within the scope of the present invention, and protected by the accompanying claims.

  The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

1 is a schematic side cross-sectional view of an exemplary detector according to the prior art. FIG. 1 is a schematic diagram illustrating a simplified dual element pyroelectric detector with schematic optical elements and electronics according to the prior art. FIG. FIG. 3 is a schematic diagram representing an object of interest and background in the field of view of an exemplary detector. FIG. 2B depicts the signal, background, and total amplitude of the scene illustrated by FIG. 2A over time. 1 is a schematic diagram of a first embodiment of a motion and presence sensing device. FIG. FIG. 6 is a schematic diagram of a second embodiment of a motion and presence sensing device. It is a schematic diagram illustrating an example of a system for executing the function of the present invention. 2 is a flowchart of an exemplary method for distinguishing a single element thermal sensor signal from a background. FIG. 6 is a schematic diagram of a third embodiment of a motion and presence sensing device.

  The following definitions are useful for the interpretation of terms applied to the features of the embodiments disclosed herein and are intended only to define elements within this disclosure.

  As used herein, “detector” refers to a temperature sensitive device comprising one or more temperature sensitive elements. Single element detectors include a single temperature sensitive element, while multi-element detectors include two or more temperature sensitive elements. For example, a multi-element detector may include hundreds or thousands of individual thermal sensors or pixels.

  Reference will now be made in detail to embodiments of the invention. Examples of these embodiments are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.

  The first exemplary embodiment of the motion sensing device 300 shown in FIG. 3 may be operated by a single element detector 325. The single element detector 325 is a very slow variation of radiation up to a static case, such as a thermopile, bolometer, photonic sensor, and / or semiconductor-based IR sensor (bulk or epitaxial, intrinsic or incidental, etc.). It may be similar to a typical detector 100 (FIG. 1) having a single sensing element 102 (FIG. 1) that can still be sensed. Single element detector 325 is generally configured to produce a direct current (DC) current or voltage output that is approximately proportional to the amount of thermal energy received. Such a single element detector 325 may optionally be equipped with a scrambled optical element 104 (FIG. 1).

  Compared to the previous detector, in the first embodiment, the warm object can move in any direction (as opposed to the conventional approach with a divided space) and the movement is generally a motion sensing device. This causes a change in the radiation received by 300 over time. Normally, the steady state ambient background can be measured and subtracted from the output of the motion sensing device 300. However, changes in ambient background over time effectively defeat this approach.

  Warm foreground objects can be distinguished from the background (eg, changes in ambient temperature) by time-based signal analysis. This first embodiment applies a background model that may have different functionality, such as signal rise or fall time, signal format, and signal amplitude. This model can be used to filter / separate the background from signals with significantly different functionality in time.

  To illustrate this idea, the following simple example is illustrated by FIGS. 2A and 2B. An object of interest 250, such as a person, is in the FOV 290 of the single element detector 325, and the FOV 290 is exposed to sunlight, for example, through a window in the surveillance space. The sun 260 is shining but the clouds 270 are passing, so that the monitored background area in the FOV 290 of the single element detector 325 randomly heats and cools. The object of interest 250 is moving in the FOV 290 toward the single element detector 325. The amount of radiation originating from the object of interest received by the sensor is referred to as a “signal”, which is represented by the dashed line in FIG. 2B and increases as the object of interest approaches the single element detector 325. The signal 281 can be subtracted from the background 282 represented by a dashed line. The total output of the single element detector 325 represents the sum 280 of the signal 281 and the background 282 and is shown as a solid line in the graph of FIG. 2B. Since the signal 281 rises significantly faster than the background 282, the background 282 is filtered by applying a simple low pass with a time constant comparable to the background time constant, so that the filtered signal totals 280. Can be subtracted from. What remains is a signal 281 that can be analyzed by a simple threshold.

  In other embodiments, a model of the signal viewed by the single element detector 325 can be applied to the sum. In that case, a simple difference between the filtered signal and the filtered background may be evaluated using a threshold. In order to further improve the distinction between signal and background, this basic principle may be applied to more elaborate signal analysis, such as in particular Fast Fourier Transform (FFT), function fitting, machine learning and modeling. . This principle is not limited to the time domain, but may be implemented by any other mathematical transformation, such as frequency domain, Laplace transform, multivariate expansion, and the like.

  The first embodiment is not limited to the above example. As long as the temporal behavior of the radiation of both heat sources can be modeled and / or explained in a separable manner, any heat source can be referred to as a “signal” and another heat source as a “background”. For example, the background may be a person moving at a distance from the sensor, and the signal may be a person moving in the foreground of the FOV. The background / signal may be a heat source (car, pet, person, fire, etc.) that produces different radiation dose amplitudes but the same spatial position. The embodiments described herein are not limited to spatial variation. For example, the detector 300 can distinguish a local fire from a heater, or a pet / child can be distinguished from an adult human.

  Exemplary embodiments of the present invention include a single element background differential thermopile sensor (TP) that can be operated without additional optical elements such as multifocal Fresnel lenses.

  In a first embodiment, a detector including a thermopile sensor provides a current or voltage proportional to net radiation and senses a DC component. Thus, a resting heat spot, such as a stationary human, can be sensed after being separated from any detected background radiation that can be generated by a heater, changing solar load, air conditioning, and the like. The first embodiment incorporates background subtraction by the modeling technique described in detail below.

  The simplest background difference can be realized by measuring the net radiation without the presence of the object of interest, whereby only the background is measured. The recorded value is used as an offset to be subtracted from the sensor output. An object that moves into the field of view of the TP can be recognized by a simple threshold of the signal minus the offset. However, a simple background difference may not be sufficient if the ambient conditions change over time, thereby invalidating the offset.

  FIG. 3 is a schematic diagram of a first embodiment of a sensing device 300. IR radiation 310 includes a signal 312 from a warm object, eg, person 250 (FIG. 2A), and background radiation 314, eg, ambient heat within the FOV of sensing device 300. Sensing device 300 recognizes the presence and / or movement of warm objects in the FOV and generates an action of switch 380, for example. For example, the switch 380 can be activated as a result of the detection and / or non-detection of warm objects in the FOV. Device 300 splits the raw output of single element detector 325 and processes the background and signal independently to determine the action of switch 380. In other embodiments, the output of the sensing device 300 may be something other than the switch 380, such as an output signal, or a visual indicator such as an indicator lamp or an indicator icon on the display monitor.

  Single element detector 325 detects IR radiation 310 along with some noise 320, eg, self noise or system noise. The single element detector 325 is a raw data output 330 that is proportional to the received net IR radiation 310, eg, an analog voltage / current level, or a digital conversion of such an analog output signal, eg, by an analog-to-digital converter (ADC). I will provide a. However, in a third embodiment to be described later, a multi-sensor detector may generate a plurality of output signals from each sensor and / or collect output signals from each of the sensors. For the first embodiment, the single element detector 325 has a single sensor that produces a single raw detector output 330.

  The raw detector output 330 may be split, for example by a multiplexer (not shown), and fed to more than one data analysis branch. For simplicity, only two branches are described in the first embodiment. However, in alternative embodiments, more than two branches may be used, eg, to distinguish multiple signals from each other and the background. The first branch is fed to a first transform filter 340 that produces a filtered background 345 and the second branch is routed to the input of a second transform filter 350 that produces a filtered signal 355. . The first transform filter 340 may transform the raw data as a function of time into a variable that can separate the background from the signal and noise, so that the filtered background signal 345 Brought about. The second transform filter 350 may transform the raw data as a function of time into a variable that can separate the signal from background and noise. The transform filters 340, 350 can be operated with variable parameters, such as background model parameters 342 and signal model parameters 352, such as frequency ranges, amplitude ranges, and the like.

  In general, the first conversion filter 340 and the second conversion filter 350 may have different mathematical operations. Before a decision to change the state of the switch 380 is made, a comparison performed, for example, by a rating device 370, eg, a comparator, is performed to distinguish the filtered background 345 from the filtered signal 355. For example, the rating may indicate that the filtered signal 355 is sufficiently distinguishable from the filtered background 345 to indicate the presence / absence / motion of a warm object in the FOV of the motion sensing device 300. Rating 370 may access a wealth of rating model parameters 372, such as thresholds, time constants, tolerance windows, signal variance indicators, and the like.

  FIG. 4 shows a second exemplary embodiment of the motion sensing device 400. A liquid crystal display (LCD) screen with an integrated single channel thermopile 425 senses IR radiation 410 from an approaching person while the sun is heating the surrounding space within the FOV of the motion sensing device. It is desirable to be able to. The single channel thermopile 425 senses a slowly rising component 414 from the sun and a rapidly rising signal component 212 from a person. Applying the first transform filter 440, for example, the low pass filter removes the signal component and ADC variation 420 with a cut-on rise time 442 of 8 seconds for the thermopile ADC output 430 signal and filtered background 445. Is generated. While the filtered background 445 can be subtracted from the thermopile ADC output 430, the second transform filter 450, eg, a low pass filter, has a background component with a 1 second cut-on rise time 452 relative to the thermopile ADC output 430 signal. And ADC variation 420 is removed and a filtered signal 455 is generated. A threshold comparator 470 may be applied to perform an action, eg, an interrupt 480 that is used to turn on the LCD in the LCD display 425.

  The threshold comparator 470 may access one or more sets of threshold parameters 472 that the transform filters 440, 450 may access to adapt to different detection scenarios. For example, the background may be an air flow that provides a fast change in raw data output due to turbulence. If the background variation is faster than human movement, the low-pass filter stage separates the signal not only from ADC variation but also from turbulence. This improves the result after subtracting the filtered background 445 from the filtered signal 455. Changing a signal or parameters of one or more of the signals to a higher cut-off value, even if the person is within the field of view of the sensor 425, where the signal of the person moving in front of the sensor 425 will trigger further events. Even in this case, the signal can be suppressed. With such higher cut-off parameters, the delay can be manipulated to switch the sensor 425 so that a person passing the FOV of the sensor 425 can be distinguished from a stationary person.

  Changing the filter parameters of the first conversion filter 440 and the second conversion filter 450 can be used to distinguish a rapid temperature change from a slow one temperature, for example, power electronics during combustion. Similarly, apart from performing a filter operation, distinguishing two or more inputs to the thermopile 425 can be accomplished using other types of mathematical operations.

  Returning to FIG. 3, the model can be applied to a thermopile ADC signal as a function of time. This model is based on a specific signature, such as a signature signal generated by a person walking through the FOV of a single element detector 325 (FIG. 3), a dog passing the FOV, and a car passing the FOV. It is for recognizing. These three cases can be distinguished by a combination of signal amplitude, signal speed, and ultimately signal pattern. This model can be analyzed by multivariate expansion. When raw data is passed through this filtering stage, the likelihood that an object passing through the FOV is a person, car or pet is generated. The output of the device may be a likelihood estimate indicating the closest match. A Fourier transform may be used for the periodic signal. For example, a Fast Fourier Transform (FFT) output can distinguish a periodic background from an aperiodic signal.

  The background component is applied with a model according to the background signature as a function of time. This model can be determined in a variety of different ways. For example, the model may provide a dynamic analysis of detector output 350 without resorting to previously stored (stored) data.

  Analysis is done by removing the background with a filter and subtracting it later. For example, if the signal fluctuates very slowly, a simple low-pass stage may be applied that does not respond to fast changes in the thermopile output as the object is moving in the field of view. This result can be improved by "filtering" the signal with a faster low-pass response and also subtracting later.

  For example, if the signature of background IR radiation 314 is predictable by a model, the signature of background IR radiation 314 may be applied directly. This learning procedure may be implemented in parameter space, which would be suitable for separating the background 345 from the signal 355. The learning procedure may be implemented by mathematical (multi-) variable expansion, where the data is transformed into the frequency domain or other domains, for example Fourier transform, Laplace transform or others. Alternatively or additionally, learning can also be performed in the time domain.

  FIG. 6 illustrates an exemplary embodiment of a method 600 for distinguishing background attention signals from the output of a single element infrared (IR) sensor 325 (FIG. 3). The steps of method 600 are performed with reference to the elements illustrated by FIG. However, those skilled in the art will appreciate that this method is also applicable to the multi-element IR sensor of FIG. As will be understood by those skilled in the art of the technical field of the present invention, any processing explanation or block in the flowchart is one for realizing a specific logical function in the processing. It should be understood that it represents a module, segment, code portion, or step that includes the above instructions, and is illustrated or described, including substantially simultaneous or reverse order, depending on the function involved. Alternative implementations in which the functions may be performed in an order other than those included are within the scope of the invention.

  The DC output 330 from the IR sensor 325 is split into a first portion and a second portion, for example via a multiplexer (not shown), as indicated by block 610. The first portion is transformed by a first transformation filter 340, as indicated by block 620, to produce a filtered background 345.

  The second portion is transformed by a second transformation filter 350 as indicated by block 630 to produce a filtered signal 355. The filtered signal and the filtered background are compared, for example by a rating 770, as shown by block 640, to distinguish the signal from the background. Rating 770 may access a rich set of rating model parameters 772, for example, to accommodate different comparison scenarios. The filtered signal is compared to the stored signal signature, as indicated by block 650. For example, whether the stored signal signature matches the stored signal signature, or whether the filtered signal 355 and / or filtered background 345 is similar in one or more aspects May include a series of parameters and / or thresholds used in the comparison step to determine. If the filtered signal is identified as indicated by block 660, for example, if the filtered signal matches a stored signal signature, an action is performed as indicated by block 670. For example, switch 380 is activated. Alternatively, action 670 may be performed if the filtered signal 355 is not clearly identified but is clearly different from the filtered background 345.

  Although the term “filter” is used herein with respect to the first conversion filter 340 and the second conversion filter 350, those skilled in the art will recognize the first filter 340 and / or the second filter 350. Will be appreciated that may include other mathematical modeling processes in the time domain and / or frequency domain in addition to or instead of conventional high pass, low pass, band pass, or notch filtering. For example, the first transform filter 340 and / or the second transform filter 350 may include, among other operations, a function on the raw detector output 330, a Fourier transform such as FFT, a Laplace transform, and a multivariate expansion fit. .

  FIG. 7 shows a third embodiment of a motion sensing device 700 in which a multi-element sensor (detector) 725 is used instead of the single-element sensor 325 (FIG. 3) of the first embodiment. Multi-element sensor 725 may have two, three, four, or more elements, such as a multi-pixel sensor.

  A third exemplary embodiment of the sensing device 700 shown in FIG. 7 is for static cases, such as thermopiles, bolometers, photonic sensors, semiconductor-based IR sensors (bulk or epitaxial, intrinsic or incidental, etc.) May be operated by a multi-element detector 725 having a plurality of sensing elements that can sense even very slow fluctuations in radiation. Multi-element detector 725 is generally configured to produce a direct current (DC) output that is approximately proportional to the amount of thermal energy received. Such a multi-element detector 725 may optionally be equipped with a scrambled optical element 104 (FIG. 1).

  IR radiation 310 may include a signal 312 from a warm object, such as person 250 (FIG. 2A), and background radiation 314, such as ambient heat. Sensing device 700 recognizes the presence and / or movement of a warm object and generates an action for switch 380. For example, the switch 380 can be activated as a result of the detection and / or non-detection of warm objects. Sensing device 700 divides the multi-element detector 725 signal into two or more branches and processes the background and signal independently to determine the action of switch 380. In other embodiments, the output of the system may be something other than switch 380, such as an output signal, or an indicator found on a display device or monitor.

  Multi-element detector 725 detects IR radiation along with some noise 320, eg, self noise or system noise. The multi-element detector 725 may provide a raw multi-sensor output 730 proportional to the received net IR radiation 310, eg, an analog voltage / current level, or digital of such an analog output signal, eg, by an analog-to-digital converter (ADC). Provide conversion. For the third embodiment, the multi-element detector 725 has two or more sensors that produce a raw multi-sensor output 730.

  The raw multi-sensor output 730 can be split and fed to more than one data analysis branch. The first branch is fed to a first transformation filter 740 that produces a filtered background 745 and the second branch is routed to the input of a second transformation filter 750 that produces a filtered signal 755. . The first transform filter 740 transforms the raw data as a function of time into a variable that can separate the background from the signal and noise, resulting in a filtered background signal 745. The second conversion filter 750 may convert the raw multi-sensor output 730 as a function of time into a variable that can separate the signal from background and noise. The transform filters 740, 750 can be operated with variable parameters, such as background model parameters 742 and signal model parameters 752.

  In general, the first transform filter 740 and the second transform filter 750 may have different mathematical operations. If the background is sensed and / or distinguished from the signal, a comparison is made, for example by rating 770, before a decision to change the state of switch 380 is made.

  As mentioned above, the system of the present invention that performs the functions detailed above may be a computer, an example of which is shown in the schematic diagram of FIG. The system 500 includes a processor 502, a storage device 504, a memory 506 storing software 508 defining the functions described above, an input and output (I / O) device 510 (or peripheral device), and And a local bus or local interface 512 that enables communication. The local interface 512 may be, for example, but not limited to, one or more buses or other wired or wireless connections, as is known in the art. The local interface 512 may have additional elements such as controllers, buffers (caches), drivers, repeaters, and receivers to allow communication, which are omitted for simplicity. . The local interface 512 may also include address, control, and / or data connections to allow proper communication between the aforementioned components.

  The processor 502 is a hardware device that executes software, particularly software stored in the memory 506. The processor 502 can be any custom or commercially available single or multi-core processor, central processing unit (CPU), an auxiliary processor of several processors associated with the system 500 (in the form of a microchip or chipset). It can be a semiconductor-based microprocessor, a macro processor, or generally any device for executing software instructions.

  The memory 506 is one of a volatile memory element (for example, random access memory (RAM such as DRAM, SRAM, SDRAM, etc.)) and a non-volatile memory element (for example, ROM, hard drive, tape, CDROM, etc.), or any of these. Combinations can be included. The memory 506 may also contain electronic, magnetic, optical, and / or other types of storage media. Note that the memory 506 may have a distributed architecture in which various components are remote from each other but accessible by the processor 502.

  In accordance with the present invention, software 508 defines the functions performed by system 500. Software 508 in memory 506 may include one or more separate programs, each of which includes an ordered list of executable instructions for implementing the logical functions of system 500, as described below. Including. Memory 506 may include an operating system (O / S) 520. The operating system inherently controls the execution of programs in the system 500 and provides scheduling, input-output control, file and data management, memory management, and communication control and related services.

  The I / O device 510 may include an input device such as, but not limited to, a keyboard, a mouse, a scanner, a microphone, and the like. Further, the I / O device 510 may include an output device such as, but not limited to, a printer and a display device. The I / O device 510 may further include, for example, a modulator / demodulator (modem; for accessing another device, system, or network), radio frequency (RF) or other transceiver, telephone interface, bridge, It may include a router or other device that communicates through both input and output, including but not limited to.

  When the system 500 is in operation, the processor 502 executes the software 508 stored in the memory 506, communicates data to and from the memory 506, and the system 500 for the software 508 as described above. The operation is generally controlled.

  When the functions of system 500 are in operation, processor 502 executes software 508 stored in memory 506, communicates data to and from memory 506, and performs operations of system 500 with respect to software 508. It is comprised so that it may generally control. The operating system 520 is read by the processor 502, possibly buffered in the processor 502, and then executed.

  When system 500 is implemented with software 508, the instructions for implementing system 500 may be stored on any computer-readable medium used by or in connection with any computer-related device, system, or method. Please be careful. Such computer-readable media corresponds to either or both of memory 506 and storage device 504 in some embodiments. In the context of this document, a computer-readable medium is an electronic, magnetic, optical, which can contain or store a computer program used by or in connection with a computer-related device, system, or method. Or any other physical device or means. The instructions for implementing the system may be embodied on any computer readable medium used by or in connection with a processor or other such instruction execution system, apparatus, or device. Although reference is made to the processor 502 as an example, such an instruction execution system, apparatus, or device, in some embodiments, may be any computer-based system, a system that includes a processor, or an instruction execution system, It may be another system that can retrieve an instruction from an apparatus or device and execute the instruction. In the context of this document, a “computer readable medium” stores, communicates and propagates a program used by or in connection with a processor or other such instruction execution system, apparatus or device, Or any means that can be transported.

  Such computer-readable media can be, for example but not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, devices, or propagation media. More specific examples of computer-readable media (not a complete list) would include: electrical connection (electronic) with one or more wires, portable computer diskette (magnetic ), Random access memory (RAM) (electronic), read only memory (ROM) (electronic), erasable programmable read only memory (EPROM, EEPROM, or flash memory) (electronic), optical fiber (optical) ), And portable compact disc read only memory (CDROM) (optical). It should be noted that the computer readable medium may be paper on which the program is printed or even another suitable medium. This means that the program is captured electronically, for example via optical scanning of paper or other media, and then compiled, interpreted, or processed in an appropriate manner if necessary and then stored in computer memory. This is because it is possible.

  In an alternative embodiment in which system 500 is implemented in hardware, system 500 can be implemented by any one or combination of the following techniques, each well known in the prior art: depending on the data signal Discrete logic circuits having logic gates for implementing logic functions, application specific integrated circuits (ASIC) having appropriate combinational logic gates, programmable gate arrays (PGA), field programmable gate arrays (FPGA), and the like.

  It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. For example, in some embodiments, the difference between two low-pass filtered signals is determined not only by measuring the presence of a person entering the field of view but by measuring a positive value above a threshold value. It may also be perceived by measuring the absence of a signal after leaving the field of view. A person may be considered to be part of the background, for example when the person rests longer than the time constant of the background filter.

  In some embodiments, the time constant of the background filter (as well as the signal filter) is used to quickly zero out (reset) the difference between the two filters when an object is sensed and to sense the absence of the object. In order to be prepared, it may be reduced to a fast response. As the object leaves the field of view again, a fast filter setting can be selected to reset the system in case the same or a different object enters the FOV.

  It may be realized that the periodic behavior of the background is subtracted in order to predict the background. This can be a simple case, such as day and night temperature fluctuations, or it can be extended to machine learning by recording the repetitive behavior of any background.

  In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.

Claims (16)

An infrared (IR) sensor configured to receive a signal IR from a warm object and a background IR and generate a DC output;
A first transform filter configured to receive the DC output and generate a filtered background via a first time-based signal analysis ;
A second transform filter configured to receive the DC output and generate a filtered signal via a second time-based signal analysis ;
Comparing the filtered signal with the filtered background and based on the detected difference between the filtered signal and the filtered background based on temporal functionality A rating configured to generate a result signal;
With
The IR sensor is a single element sensor.   The device of claim 1, further comprising an analog-to-digital converter (ADC) configured to convert the direct current output to a digital representation.   The device of claim 1, further comprising a switch configured to receive the result signal and to operate according to the received result signal.   The device of claim 1, further comprising a first memory in communication with the first transform filter configured to store background model parameters.   The device of claim 4, further comprising a second memory in communication with the second transform filter configured to store signal model parameters.   6. The device of claim 5, further comprising a third memory in communication with the rating configured to store rating model parameters. The first conversion filter and / or the second conversion filter are:
Fourier transform and;
With Laplace transform;
Multivariate expansion,
The device of claim 1, selected from the group consisting of: A method of distinguishing background signal of interest from the output of a single element infrared (IR) sensor:
Dividing the direct current output from the IR sensor into a first part and a second part;
Transforming the first portion with a first time-based transform filter to generate a filtered background;
Transforming the second portion with a second time-based transform filter to generate a filtered signal;
Comparing the filtered signal and the filtered background to distinguish the filtered signal from the background based on temporal functionality ;
Comparing the filtered signal with a stored signal signature;
Performing a first action if the filtered signal matches the stored signal signature;
A method comprising: 9. The method of claim 8 , further comprising obtaining a set of background model parameters to isolate the filtered background. The method of claim 9 , further comprising applying the background model parameters to the first transform filter. 9. The method of claim 8 , further comprising obtaining a set of signal model parameters and isolating the filtered signal. The method of claim 11 , further comprising applying the signal model parameters to the second transform filter. 9. The method of claim 8 , further comprising obtaining a set of rating model parameters. An infrared (IR) sensor configured to receive a signal IR from a warm object and a background IR and generate a DC output;
A first transform filter configured to receive the DC output and generate a filtered background via a first time-based signal analysis ;
A second transform filter configured to receive the DC output and generate a filtered signal via a second time-based signal analysis ;
Comparing the filtered signal with the filtered background and based on the detected difference between the filtered signal and the filtered background based on temporal functionality A rating configured to generate a result signal;
With
The IR sensor comprises a plurality of sensing elements. The rating model parameter includes one or more of a group consisting of a threshold value, a time constant, a tolerance window, and a signal dispersion indicator,
The rating is configured to access parameters of the rating model parameter to compare the filtered signal with the filtered background.
The device of claim 6. Further comprising a storage device for storing a plurality of rating model parameters consisting of one or more of the group consisting of a threshold, a time constant, a tolerance window, and a signal dispersion indicator;
The rating is configured to access parameters of the plurality of rating model parameters to compare the filtered signal with the filtered background;
The device of claim 14.